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What is motor neuron disease?

“Motor neuron disease” is a term used to describe a group of disorders in which the motor neurons in the spine and brain gradually lose function. They’re a type of neurodegenerative disease that’s uncommon yet deadly.

Motor neurons are nerve cells that produce electrical output signals to muscles, determining how well they work.

Motor neuron disease (MND) can strike at any age, although it is more common after the age of 50. Males are more affected than females. Amyotrophic lateral sclerosis (ALS) is the most frequent kind of MND .

Stephen Hawking, a well-known English scientist, died in March 2018 after a long battle with ALS. Lou Gehrig, an American baseball player, had ALS as well. As a result, it was named Lou Gehrig’s disease.

Causes

Helen Carmichael at her home in Feltham. Photograph: Sophia Evans/The Observer
Helen Carmichael at her home in Feltham. Photograph: Sophia Evans/The Observer

Motor neurons provide messages from the brain to the muscles, instructing them to move. Swallowing and breathing are examples of conscious and automatic movements in which they have a role.

Experts estimate that about 10% of MNDs are inherited. The remaining 90% develop at random.

The specific causes are unknown, although genetic, toxic, viral, and other environmental variables may have a role, according to the National Institute of Neurological Diseases and Stroke.

Types

There are numerous forms of MNDT. Doctors categorize them based on whether or not they are inherited and which neurons they impact. The types include:

  • ALS: The most prevalent kind of MND is this one. It affects both upper and lower motor neurons (brain and spinal cord neurons), which subsequently affects the muscles of the arms, legs, mouth, and respiratory system. People with ALS survive for 3–5 years on average after being diagnosed, however some people can live for 10 years or more with supportive care.
  • Primary lateral sclerosis: This has an effect on the brain’s neurons. It’s an uncommon kind of MND that progresses slower than ALS. It is not lethal, but it can have a negative impact on one’s quality of life. Kids develop juvenile primary lateral sclerosis.
  • Progressive bulbar palsy (PBP): This affects the brain stem, and patients with ALS are more likely to develop PBP. It causes choking spells on a regular basis, as well as difficulties speaking, eating, and swallowing.
  • Progressive muscular atrophy: This kind of MND is quite uncommon. It affects the lower motor neurons in the spinal cord, causing muscle atrophy over time, particularly in the arms, legs, and mouth.
  • Spinal muscular atrophy (SMA): This hereditary MND develops in children. There are three varieties, all of which are caused by the SMA1 genetic mutation. The trunk, legs, and arms are usually affected. The long-term outlook varies according on the type.

Symptoms

There are three phases of MND, each with its own set of symptoms: early, middle, and advanced. The illnesses advance at different rates and have varied degrees of severity.

Early stage signs and symptoms

Symptoms of MND develop slowly in the early stages and might be confused with those of other illnesses. The symptoms vary depending on the kind of MND and the body part affected.

Symptoms usually start in one of the following areas:

  • the arms and legs
  • the mouth
  • the respiratory system

They may include the following:

  • a weakening grip, which makes it hard to pick up and hold things
  • fatigue
  • muscle pains, cramps, and twitches
  • slurred speech
  • weakness in the arms and legs
  • clumsiness and stumbling
  • difficulty swallowing
  • trouble breathing or shortness of breath
  • inappropriate emotional responses, such as laughing or crying
  • weight loss, as muscles lose their mass

Middle stage signs and symptoms

Early symptoms get increasingly severe as the illness advances. People may also have the following symptoms:

  • muscle shrinkage
  • difficulty moving
  • joint pain
  • drooling, due to problems with swallowing
  • uncontrollable yawning, which can lead to jaw pain
  • changes in personality and emotional states
  • difficulty breathing

According to a 2017 research, up to half of people with ALS have brain involvement, which includes memory and language issues. It also mentions that 12–15 percent of ALS people acquire dementia. Insomnia, anxiety, and sadness are common side effects for some people.

Advanced stage signs and symptoms

A person with advanced ALS will eventually require assistance moving, eating, breathing, or a combination of these. Breathing issues are the most prevalent cause of mortality in people who have this disease.

Risk factors

Depending on the kind of MND, it might affect adults or children. Males are more susceptible to these illnesses than females. At birth, inherited forms may be present. MND symptoms, on the other hand, are more likely to occur beyond the age of 50.

There appear to be some differences in risk factors among the various categories. SMA, for example, is usually inherited, although not all kinds of MND are. In the United States, about 10% of ALS cases are inherited.

Veterans appear to have a 1.5 to 2.0 times higher likelihood of acquiring ALS than nonveterans, according to the National Institute of Neurological Diseases and Stroke. This might mean that being exposed to specific chemicals raises the likelihood of developing ALS.

Furthermore, compared to the general population, professional football players had a greater chance of dying from ALS, Alzheimer’s disease, and other neurological disorders, according to a 2012 research. Experts believe there may be a relationship between this and recurring head injuries.

Diagnosis

Doctors typically have a hard time diagnosing MND in its early stages since it might seem like other diseases like multiple sclerosis.

If a doctor believes someone has MND, they will be referred to a neurologist, who will do a comprehensive examination and obtain a medical history. They could also request testing such as:

  • Blood and urine tests: These can be used to rule out other illnesses and identify any increases in creatine kinase, a chemical produced when muscles break down.
  • MRI brain scan: An MRI cannot detect MND, but it can help rule out other conditions, such as a stroke, a brain tumor, or unusual brain structures.
  • Electromyography (EMG) and nerve conduction study (NCS): The quantity of electrical activity in muscles is measured by an EMG, whereas the speed at which electricity flows through muscles is measured by an NCS.
  • Spinal tap, or lumbar puncture: A sample of cerebrospinal fluid, which surrounds the brain and spinal cord, is taken by a doctor. This can be used to rule out other possibilities.
  • Muscle biopsy: This can aid in the detection or exclusion of a muscle condition.

After the testing, the medical team observes the person for a period of time before verifying that they have MND.

Treatment

MND is no cure, however therapy can help to halt its course and increase a person’s independence and comfort. Medication, assistive gadgets, and physical therapy can all be beneficial.

Treatment options are determined by factors such as:

  • the form of MND
  • the type and severity of symptoms
  • personal needs and wishes
  • the availability and affordability of drugs

Slowing disease progression

Some medications appear to be useful in reducing the development of some MND. Edaravone (Radicava) is used to treat ALS, while nusinersen (Spinraza) and onasemnogene abeparvovec (Zolgensma) are used to treat SMA.

Muscle cramps and stiffness

Botulinum toxin (Botox) and other medications can assist. Botox injections can temporarily stop the brain from sending signals to the stiff muscles.

Muscular relaxants like Baclofen (Lioresal) can aid with muscle stiffness, spasms, and yawning. A tiny pump can be surgically implanted to administer regular dosages to the area around the spinal cord by a doctor. The medication then travels to the nervous system.

Physical therapy may also help relieve cramps and stiffness in some people.

Pain reduction

Ibuprofen (Advil, Motrin) is a nonsteroidal anti-inflammatory medicine that can aid with mild to severe muscle cramping and spasms.

In more advanced phases of severe joint and muscular pain, a doctor may prescribe stronger pain management drugs.

Other alternatives

Scopolamine is a drooling drug that is absorbed into the body by a patch on the skin. Antidepressants may aid with emotional lability, which is defined as uncontrolled laughter or crying.

Other drugs can aid with pseudobulbar affect, which is a medical name for unexpected bursts of laughter or tears. Dextromethopan hydrobromide is one option (Neudexta).

Assistive devices and therapies

A person may require specific gadgets to assist with:

  • moving around
  • communicating
  • feeding and swallowing
  • breathing

Some technologies can help a person remain independent for extended periods of time, while others can help them live longer. Ventilators and feeding tubes, for example, can help with breathing and nourishment.

Communication and swallowing can both benefit from speech and language therapy. Physical and occupational therapy can assist a person in maintaining mobility and function while also assisting them in learning new methods to do certain activities.

Conclusion

The outlook for people with MND varies dramatically depending on the type of disease they have.

SMA people, for example, should expect to live a normal life span. Other varieties of MND can shorten one’s lifespan.

New drugs are being developed to assist reduce the growth of MND. Researchers are also looking at how stem cells might be used to heal related damage in the hopes of developing a cure one day.

Sources

  • http://www.smafoundation.org/development/pipeline/
  • https://www.medicalnewstoday.com/articles/164342
  • https://www.mda.org/disease/amyotrophic-lateral-sclerosis/signs-and-symptoms/stages-of-als
  • https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Amyotrophic-Lateral-Sclerosis-ALS-Fact-Sheet
  • https://ghr.nlm.nih.gov/condition/juvenile-primary-lateral-sclerosis
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4098841/
  • https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5220336/
  • http://www.nhs.uk/conditions/Motor-neurone-disease/Pages/Introduction.aspx
  • https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Motor-Neuron-Diseases-Fact-Sheet
  • https://www.eurostemcell.org/motor-neurone-disease-how-could-stem-cells-help
  • http://www.alsa.org/about-als/symptoms.html

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